Water dripping from a rooftop evaporative cooler usually traces to the water-management parts — a stuck float valve, blocked overflow, split distribution lines or an ageing tank. Here’s what causes it and how it’s fixed.
7 min read FreshDuct Melbourne Melbourne, Victoria
Water dripping from a rooftop evaporative cooler usually traces to the water-management parts — a stuck float valve, blocked overflow, split distribution lines or an ageing tank. Here’s what causes it and how it’s fixed.
Water PartsFloat, overflow, lines, tank
Act EarlyRoof leaks cause damage
Service FixDiagnose & resolve the cause
Most evaporative cooler leaks come from the water-management parts — a stuck float valve overfilling the tank, a blocked overflow, split distribution lines, or an ageing tank/seal. A service identifies which and resolves it.
Why Is It Leaking?
A rooftop evaporative cooler moves a lot of water — it’s constantly wetting the pads to cool the air — so when it leaks, the cause is almost always in the water-management parts: the float valve, the tank and overflow, or the distribution lines that feed water to the pads. Because the unit sits on the roof, any leak can track into the roof and ceiling, so it’s worth identifying and fixing promptly (see the causes above).
The Main Causes
Stuck float valve — the valve that controls the water level sticks open, the tank overfills and spills. Blocked overflow — water can’t drain and backs up. Split or loose distribution lines — the small lines feeding water to the pads leak. Cracked tank or perished seal — on an ageing unit, the base or seals leak. A service checks each and resolves the actual cause.
Leaks Into the Roof
The reason a leaking evaporative cooler matters more than it might seem is its location. Sitting on the roof, leaking water can run into the roof cavity, then the ceiling and walls, causing staining, damp and damage over time. A leak you can see dripping outside is one thing; water tracking unseen into the roof is the real risk. This is why a leaking rooftop cooler is worth prompt attention.
What to Do
If you notice water leaking or staining near the cooler or on the ceiling below it, turn the cooler off (and its water supply if you can access it) to stop more water entering, and have it checked. Avoid running a unit that’s leaking into the roof. If it’s the off-season, draining and winterising the unit prevents leaks. See our winterising guide.
When to Call
Call for a service if the cooler is overflowing, dripping, or you see water staining on the ceiling below it. A technician will diagnose the float valve, overflow, distribution lines and tank, and fix the cause — usually a straightforward water-management repair. Catching it early avoids roof and ceiling damage. See our cooler not working guide for other faults.
Frequently Asked Questions
Why is my evaporative cooler leaking water?
Most leaks come from the cooler’s water-management components: a float valve stuck open so the tank overfills and spills, a blocked overflow, split or loose water-distribution lines that feed the pads, or a cracked tank or perished seal on an ageing unit. Because the cooler sits on the roof, a leak can track into the roof and ceiling, so it’s worth addressing promptly. A service identifies the specific cause and fixes it.
Is a leaking rooftop evaporative cooler serious?
It can be — because the unit is on the roof, leaking water can find its way into the roof cavity, ceiling and walls, causing staining and damage over time. A small drip noticed early is easy to fix; a persistent leak left alone risks ceiling damage. So while it’s not dangerous to you, it’s worth getting a leaking rooftop cooler checked promptly to protect the building.
Why does my evaporative cooler overflow water?
Overflowing usually means the float valve that controls the water level has stuck open, so the tank keeps filling past its level and spills out the overflow — or the overflow itself is blocked, backing water up. A faulty float valve is a common, fixable cause. A technician can adjust or replace the float valve and clear the overflow to stop the overflowing.
Can a leak happen when the cooler is off for winter?
Yes — if the cooler isn’t drained and winterised, water left in the tank can leak as seals age or in freezing conditions, and a stuck-open valve can let mains water through. Proper winterising (draining the unit and shutting off its water) prevents off-season leaks and protects the unit. See our winterising guide.
How is an evaporative cooler leak fixed?
A technician diagnoses the source — checking and adjusting or replacing the float valve, clearing the overflow, repairing or replacing split distribution lines, and inspecting the tank and seals — then resolves it. Many leaks are straightforward water-management fixes done as part of a service. On a very old unit with a cracked tank, replacement of the part or unit may be advised. We diagnose and quote the fix.
Evaporative Cooler Problem or Service? Talk to FreshDuct
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